Recently, as one type of advanced batteries featuring high power and high energy density, non-aqueous electrolyte batteries of high electromotive force have been used. The non-aqueous electrolyte battery utilizes the non-aqueous electrolyte, such as a non-aqueous electrolyte solution, and a process of oxidation and reduction of lithium or the like.
Such a non-aqueous electrolyte battery has generally employed, as the negative electrode material for negative electrode, metallic lithium, lithium alloys such as a Li--Al alloy, a carbon material capable of intercalating/deintercalating lithium.
One problem encountered with the use of metallic lithium as the negative electrode material for negative electrode is that charging/discharging of the battery results in lithium dendrite growth on the negative electrode surface.
Where the lithium alloy such as Li--Al alloy is used as the negative electrode material for negative electrode, the dendrite growth does not occur. However, a low flexibility of the lithium alloy makes it difficult to fabricate a cylindrical battery wherein the negative electrode and the positive electrode, with a separator interposed therebetween, are wound into a roll.
Where the lithium alloy is used in a powdery form, a high reactivity of the lithium alloy results in a problem of difficult handling thereof. In addition, when a charge/discharge process is performed with such a lithium alloy used as the negative electrode, the charge/discharge process induces expansion/contraction of the lithium alloy, which produces a stress within the lithium alloy. This leads to another problem that the repeating of such charge/discharge processes causes destruction of the lithium alloy, resulting in capacity decline.
Where, on the other hand, the carbon material is used as the negative electrode material for negative electrode, the charge/discharge process causes less expansion/contraction of the carbon material than in the aforesaid case where the lithium alloy is used. However, some problems exist that the capacity of the carbon material is small than that of the lithium alloy and the initial charge/discharge efficiency is low.
Recently, there has been proposed, as in JP, 6-275263, A, the non-aqueous electrolyte battery which uses titanium oxide or lithium titanate as the negative electrode material for negative electrode together with a non-aqueous electrolyte solution, as the non-aqueous electrolyte, which solution is prepared by dissolving a lithium salt into a non-aqueous solvent.
Unfortunately, where titanium oxide or lithium titanate is used for the negative electrode in combination with the non-aqueous electrolyte solution prepared by dissolving the lithium salt into the non-aqueous solvent, a problem exists that the non-aqueous electrolyte solution is decomposed by a catalytic reduction induced by titanium oxide or lithium titanate contained in the negative electrode while the charge current is partially consumed for the decomposition of this non-aqueous electrolyte solution and hence, the charge/discharge efficiency is lowered.
In view of the foregoing, the invention is directed to solve the aforementioned problem encountered with the use of titanium oxide or lithium titanate as the negative electrode material for use in the negative electrode of the non-aqueous electrolyte battery including the positive electrode, the negative electrode and the non-aqueous electrolyte. An object of the invention is to provide a non-aqueous electrolyte battery which ensures a high charge/discharge efficiency by preventing the non-aqueous electrolyte from being decomposed by the catalytic reduction induced by titanium oxide or lithium titanate used for the negative electrode.